The above study involved a capsule formulation containing 25mg of carbidopa and varying amounts (25mg, 50mg, 100mg) of 5-hydroxy L-tryptophan. However, 5-hydroxy L-tryptophen being a highly fluffy and low density powder posed multifaceted manufacturing problem especially when required in higher doses. The flow and compressibility properties, both essential for capsule or tablet manufacturing on automatic machinery were poor. Also, because of non-availability of carbidopa drug powder, the commercial carbidopa tablets were to be used which restricted due to capsule size, the use of other excipients to improve the compression, and flow characteristics. Certain manipulations in the process of manufacturer were made to overcome this problem. The resulting powder mixture had good flow and compressibility and produced uniformed weight capsules with improved disintegration time.